<!DOCTYPE html>
<style>
  #subframe {
    width: 400px;
    height: 500px;
    background-color: blue;
    position: relative;
  }

  #scroller {
    height: 200px;
    width: 300px;
    position: absolute;
    overflow: scroll;
  }

  #clip {
    position: absolute;
    clip: rect(0px, 100px, 100px, 0px);
  }
</style>
<div id="scroller">
  <div id="clip">
    <iframe id="subframe"></iframe>
  </div>
</div>
<script src="../../../resources/run-after-layout-and-paint.js"></script>
<script>
if (window.internals)
  internals.settings.setPreferCompositingToLCDTextEnabled(true);
runAfterLayoutAndPaint(function() {
  clip.style.clip = "auto";
}, true);
</script>
